The Bad Sleep Habit That Can Harm Your Fertility

Here’s how your sleep cycle can affect your biological clock.

Night owls may want to consider getting some shuteye if they're thinking about having a baby. Or at least work on turning off the lights.

A new study published in Fertility and Sterility says darkness is especially important for women's reproductive health, and for fetal development in pregnant women. The magic's in melatonin, a regulating hormone produced by the brain's pineal gland and released in response to darkness. While it's primarily responsible for regulating the sleep/wake cycle, melatonin also helps protect eggs from oxidative stress, according to Russel J. Reiter, a professor of cellular biology at the University of Texas Health Science Center in San Antonio.

"Every time you turn on the light at night, this turns down the production of melatonin," says Reiter. "If women are trying to get pregnant, maintain at least eight hours of a dark period at night," he advised. "The light-dark cycle should be regular from one day to the next; otherwise, a woman's biological clock is confused."

So close the blinds, shut the laptop and ditch the Kindle. It's not necessarily sleep, but darkness, that kicks your melatonin into gear.